This relates generally to imaging systems, and more particularly, to imaging systems with global shutter functionality.
Modern electronic devices such a cellular telephones, cameras, and computers often use digital image sensors. Imagers (i.e., image sensors) often include a two-dimensional array of image sensing pixels. Each pixel typically includes a photosensor such as a photodiode that receives incident photons (light) and converts the photons into electrical signals.
Conventional image sensors are fabricated on a semiconductor substrate using complementary metal-oxide-semiconductor (CMOS) technology or charge-coupled device (CCD) technology. In CMOS image sensors, a rolling shutter or a global shutter may be used. In CMOS image sensors with a global shutter, a charge storage region is typically incorporated into each pixel to store charge from the photodiode until read out. However, incident light that is not converted to charge in the photodiode may affect the charge levels in the charge storage region. This may increase noise in the pixels and decrease the image quality of the image sensor.
It would therefore be desirable to be able to provide improved CMOS image sensors with global shutter functionality.